Swiss watchmaker IWC Schaffhausen is celebrating the 75th birthday of its Portugieser watch line with a new collection that comes with a host of technological and design modifications as well as new features, including a watch that features IWC’s new calibre and its first ever annual calendar.

The Portugieser Annual Calendar is said to bridge the gap between the perpetual calendar and the simple date display. It features the new 52850 calibre which has two barrels that keep the new function supplied with ample energy while offering a seven-day power reserve.

The watch also symbolises the launch of an IWC initiative to produce further series of in-house calibres in the years ahead.

Located at 12 o’clock on the dial, IWC’s annual calendar shows the month, date and day in three separate, semi-circular windows. The switching mechanism automatically takes into account the differing lengths of individual months. Unlike a perpetual calendar, however, the annual calendar is unable to factor in a leap year. Once a year, then, at the end of February, it requires manual correction. For the development of the annual calendar module, IWC’s watch designers ensured that the correction could be carried out easily and conveniently using the crown.

Thanks to this solution, the engineers were able to dispense with a corrector, which would have compromised the watch’s purist design.

In order to free up as much space as possible for the date display, the designers replaced the indices from 11 o’clock to 1 o’clock with the three display discs. The American order in which the date is shown was not only necessary from a technical and design point of view, but is also a homage to F A Jones, IWC’s American founder.

The small seconds sub-dial, however, is not positioned at 6 o’clock as in the original, but at 9 o’clock. The sub-dial on the opposite side contains the power reserve display.

The in-house movement with 7-day power reserve is yet another quantum leap in the history of the Portugieser family. The rare combination of an annual calendar and 168-hour calibre should make this latest complication even more attractive for watch connoisseurs, says IWC.

The watch is available in 18-carat red gold with a silver-plated dial or in stainless steel with a silver-plated or midnight blue dial. All versions are fitted with black Santoni alligator leather straps. A see-through sapphire-glass back provides an unimpeded view of the new 52850 calibre.

The new 52000-calibre family is found in four models in the new Portugieser collection.